mapLongitudeLatitudeXY is a safer alternative, if a map has
already been drawn with mapPlot(), because that function cannot
alter an existing projection. map2lonlat() is an inverse to
map2lonlat.
Other functions related to maps:
formatPosition(),
lonlat2utm(),
map2lonlat(),
mapArrows(),
mapAxis(),
mapContour(),
mapCoordinateSystem(),
mapDirectionField(),
mapGrid(),
mapImage(),
mapLines(),
mapLocator(),
mapLongitudeLatitudeXY(),
mapPlot(),
mapPoints(),
mapPolygon(),
mapScalebar(),
mapText(),
mapTissot(),
oceCRS(),
oceProject(),
shiftLongitude(),
usrLonLat(),
utm2lonlat()